Thread replenishing mechanisms for lockstitch sewing machines



March 26, 1968 H. D. CHAPLIN, JR 3,374,755

THREAD REPLENISHING MECHANISMS FOR LOCI STITCH SEWING MACHINES Filed April 26, 1965 2 Sheets-Sheet 1 INVENTOR.

HenryD. Chap/in Jz WITNESS 2 Sheets-Sheet 2 minis INVENT( Henry D. Chap United States Patent 3,374,755 THREAD REPLENTSHING MECHANISMS FOR LOCKSTITCH SEWING MACHINES Henry D. Chaplin, Jr., Cranford, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Apr. 26, 1965, Ser. No. 450,834 6 Claims. (Cl. 112-181) ABSTRACT OF THE DISCLOSURE A control mechanism is disclosed for rendering effective and ineffective devices for replenishing bobbin thread in a bobbin in place in the loop taker of a sewing machine. The control mechanism is accessible for influence by the operator through the access opening in the sewing machine which is ordinarily provided for access to the bobbin. Closing of the slide cover plate for the access opening trips latch release mechanism automatically rendering the bobbin replenishing mechanism inoperative.

This invention relates to lockstitch sewing machines of the type in which under or locking thread may be replenished on the bobbin in place in the loop-taker while the loop-taker partakes of regular motion as is required for formation of lockstitches, and more particularly, to a novel and improved mechanism whereby the machine operator may at will initiate and control the thread replenishing operation.

It is an object of this invention to provide a compact and effective bobbin thread replenishing control mechanism organized in a novel and advantageous fashion closely adjacent to the sewing machine loop-taker.

A further object of this invention is to provide a bobbin thread replenishing control mechanism so organized as to minimize the possibility of inadvertent or accidental failure to interrupt bobbin thread replenishment when work fabrics are directed to the sewing machine stitching point in readiness for a sewing operation.

This invention provides for initiation of bobbin thread replenishment by operator influenced depression of a push button which becomes accessible when the loop-taker cover plate is retracted. Interruption of the bobbin thread replenishing operation is occasioned automatically when the looptaker cover plate is closed. Since it is extremely diflicult to direct work fabric to the stitching point while the loop-taker cover plate is retracted, the possibility of inadvertent or accidental failure of the operator to interrupt bobbin thread replenishment prior to introduction of work fabrics to the stitching point in readiness for sewing is practically eliminated.

With the above and additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 is a vertical cross-sectional view of a sewing machine having this invention applied thereto,

FIG. 2 is an enlarged vertical cross-sectional view taken substantially along line 22 of FIG. 1 illustrating the position of parts when the loop-taker cover plate is closed,

FIG. 3 is a cross-sectional view similar to that illustrated in FIG. 2 but illustrating the position of parts with the loop-taker cover plate shifted into opened position and with the push button of the bobbin thread replenishing control mechanism depressed,

FIG. 4 is a cross-sectional view taken substantially along line 4-4 of FIG. 3, and

FIG. 5 is a cross-sectional View of a portion of the "ice bracket supporting the thread replenishing mechanism taken substantially along line 55 of FIG. 3.

Referring to the drawings, the sewing machine to which this invention is applied includes a frame comprising a bed 11 from which rises a standard 12 supporting a bracket arm 13 overhanging the bed. Journaled for endwise reciprocatory motion in the bracket arm is a needle bar 14 to which is secured a thread carrying needle 15 which cooperates in the formation of lockstitches with a looptaker, indicated generally at 16, which is journaled in the bed. The needle and loop-taker remain permanently interconnected for operation in timed relation as is required for the formation of lockstitches by means of the drive connections including a main shaft 17 journaled in the bracket arm and drivingly connected by means of a crank 18 and a connecting link 19 to the needle bar.

By means of meshing gear sets 20, 21 and 22, the main shaft 17 is drivingly connected by way of a standard shaft 23 and a bed shaft 24 to a loop-taker shaft 25 on which the loop-taker is secured. An electric motor 26 which may be enclosed Within the standard of the machine drives the sewing machine main shaft 17 by way of a worm 27 and a worm wheel 28 connection. The crank 18 on the main shaft which drives the needle bar also imparts oscillatory motion to the needle thread take-up lever 29 which is constrained in the bracket arm by means of an anchor link 29'.

The sewing machine illustrated in FIGS. 1 and 2 includes a work feeding mechanism of the drop feed variety including a feed dog 30 which is opposed by a spring loaded presser foot 31 carried on a presser bar 32 slidably arranged in the bracket arm. The presser bar is provided with means within the bracket arm by which the presser foot may be raised and lowered into and out of a position opposing the feed dog. With the control mechanisms for replenishment of thread on the bobbin of this invention, it is desirable that the presser foot be raised during bobbin thread replenishing operation so as to render the feed dog ineffective to advance the work. The feed dog 30 preferably works upwardly through slots 33 in a throat plate 34 secured on the sewing machine bed 11. The sewing machine bed in front of the throat plate 34, considered in the line of work feed provided by the feed dog, is formed with an access opening 35 which is arranged vertically above the loop-taker 16 and provides access to the loop-taker. The access opening 35 is provided with a removable cover plate 36 which is preferably slidably constrained in the access opening flush with the top surface of the sewing machine bed 11. The cover plate 36 may be formed with a finger grip recess 37 to facilitate the operator slidably retracting the cover plate into the position illustrated in FIG. 3 while the outer edge 38 of the cover plate may be engaged by the operator to push the cover plate into closed position as illustrated in FIG. 2. Represented at 39 in FIGS. 2 and 3 is the inner edge of the cover plate, which in the closed position, abuts the throat plate 34.

The loop-taker 16, as illustrated in FIGS. 1 and 2, may be constructed in accordance with the details disclosed in the US. Patent by S. J. Ketterer, No. 3,115,855, Dec. 31, 1963, to which reference may be had. For an understanding of this invention it is sufiicient to understand that the loop-taker includes a cup shaped rotary body portion 45 in which is journaled a bobbin case 41. A thread carrying bobbin 42 is journaled rotatably in the bobbincase and when the bobbin thread is to be replenished, the bobbin is adapted to be engaged by a bobbin winding member 43 fast on a rod 44 in an axial bore 45 in the loop-taker shaft. A collar 46 fast on the rod 44 is formed with a tang 47 accommodated in an aperture 48 in the gear 22 on the loop-taker sha-ft so as to lock the bobbin winding member for rotation with the loop-. taker. The bobbin winding member, however, may be shifted axially of the loop-taker into and out of engagement with the bobbin, and the bobbin winding member includes a drive pin 49 engageable in a notch 50 formed in the underside of the bobbin so that the bobbin will be positively driven when the bobbin winding member is shifted into. engagement therewith.

When the bobbin winding member 43 is shifted axially of the loop-taker into engagement with the bobbin, operation of the sewing machine will serve to wind on the bobbin a supply of thread from the thread carrying needle. A detailed description of this bobbin thread replenishing operation is contained in the above referenced copending U.S. Patent No. 3,115,855.

The control means for initiating and terminating bobbin thread replenishment is indicated generally at 55 in the drawings and comprises a sub-assembly of parts carried by an integral preferably stamped sheet metal bracket indicated generally at 60, which bracket is secured by fastening screws 61 in the sewing machine bed beneath a web 62 in which the loop-taker shaft 25 is journaled.

Referring to FIGS. 2, 3 and 4, the bracket 60 comprises a horizontal plate 63 through which the fastening screws 61 pass and from which depends two arms 64 and 6 5. The depending arm 64 is formed with an inturned lug 66 extending in spaced substantially parallel relation beneath the horizontal plate 63. The plate 63 and the inturned lug 66 are formed with aligned bearing apertures 67 and 68 respectively in which is slidably arranged a vertical rod 69 carrying at the upper extremity above the plate 63 a push button 70 and at the lower extremity beneath the lug 66 a stop collar 71. A down-turned finger 72 formed on the lug 66 is disposed adjacent to a flat 73, formed on the collar 71 as illustrated in FIG. to prevent turning of the rod 69.

The depending arm 65 supports a pivot pin 74 on which is journaled a fulcrum lug 75 extending from a lever 76. Threaded through one extremity of the lever 76 is a stud 77 which engages beneath the stop collar 71 on the rod 69 and which may be locked in selected position of threaded adjustment on the lever 76 by a locknut 78. The opposite extremity of the lever 76 is formed with a clearance aperture 79 which embraces a shouldered nut 80 on the bobbin winder rod 44 beneath the co'lar 46 which is fast on the bobbin winder rod. A coil spring 81 sustained in tension between the plate 63 and that extremity of the lever 76 through which the stud 77 is threaded biases the stud 77 into engagement with the stop collar 71 and further biases the rod 69 upwardly toward an extreme position as illustrated in FIG. 2 in which position the bobbin winding member 43 is lowered out of engagement with the bobbin and the sewing instrumentalities are, therefore, in a relative condition suitable for sewing. When the rod 69 is lowered as by depression of the push button 70, the lever 76 is rocked into the position illustrated in FIG. 3 in which the bobbin winding member 43 is raised into engagement with the bobbin and the parts assume a relative position suitable for bobbin thread replenishment.

Fulcrumed on a headed rivet 90 secured in the depending bracket arm 64 is a latch lever 91 formed with an inturned arm 92 extending between the horizontal plate 63 and the lug 66 of the bracket 60 and terminating in a latch finger 93 adapted to cooperate with. a notch 94 formed in the rod 69. A coil spring 95 engaging the latch lever 91 beneath the rivet 90 is anchored on a finger 96 extending from the depending arm 65 of the bracket 60 and serves to bias the latch finger 93 toward engagement in the notch 94.

An upstanding latch release arm 100 formed on the latch lever 91 extends upwardly toward the access opening 35 in the bed 11 and is positioned for engagement beneath the slide cover plate 36 as viewed in FIG. 2 constraining the latch finger 93 out of the notch 94 in the rod 69 when the slide cover plate is closed.

When the slide cover plate is opened as viewed in FIG.- 3, the latch release arm 100 will be freed for upward movement and the push button 70 will be exposed. Upon depression of the push button 70, the lever 76 will be turned so as to elevate the bobbin winding member 43 into position effective to replenish thread on the bobbin and the spring will cause the latch finger 93 to enter the notch 94 in the rod constraining the rod 69 in depressed position. Bobbin thread replenishment may then continue until the operator, viewing the bobbin through the access aperture 35 decides that sufficient thread has been wound on the bobbin.

T o interrupt the bobbin replenishing operation so as to place the parts again in position for sewing, it is necessary that the latch release arm be depressed. While the operator may contact the latch release arm directly through the access opening 35 to accomplish such depression, the latch release anm may also be depressed by the operator merely shifting the cover plate 36 into closed position. In so doing the inner edge 39 of the cover plate will cam the latch release arm 100 downwardly beneath the cover plate 36 and shift the latch finger 93 out of the notch 94.- The spring 81 will then elevate the rod 69 and turn the lever 76 into the position illustrated in FIG. 2 in which the machine is. in readiness for sewing.

Since the slide plate 36 is arranged closely adjacent to the throat plate 34 and the presser device 31, it is quite difficult to introduce work fabrics beneath the presser device when the cover plate is retracted. The work fabrics are manipulated by the operator toward the presser device over the cover plate 34 and therefore, by a sense of touch the operator will be immediately cognizant of inadvertent failure to close the cover plate. Since closure of the cover plate automatically releases the latch finger 93, inadvertent or accidental failure to interrupt the bob- 7 bin thread replenishing operation upon introduction of work fabrics to the sewing machine for sewing is obviated.

Having set forth the nature of this invention, what is claimed herein is:

1. In a lockstitch sewing machine having a frame, a loop-taker carried in said frame, a bobbin journaled in said loop-taker, said sewing machine frame being formed.

with an access aperture through which said bobbin in said loop-taker is visible to the sewing machine operator, a cover plate for said access aperture, means shiftably supporting said cover plate on said sewing machine frame for movement in a predetermined path into and out of position closing said access opening, a bobbin winding mechanism carried in said sewing machine frame for effecting replenishment of thread on said bobbin in said loop-taker, means for constraining said bobbin winding mechanism in operative bobbin winding position, and. means for automatically releasing said bobbin winding mechanism from constraint in operative position upon closure of said access opening by said cover plate, said last named means including a release arm associated with said constraining means and. extending through said access aperture into the path of movement of said cover plate.

2. In a sewing machine having a frame, a thread carrying needle and a circularly moving loop-taker carried in V the frame and operatively connected for interrelated movements as are required for the formation of lock-. stitches, a thread carrying bobbin journaled in said looptaker and a bobbin winding member interlocked for circular movement with said loop-taker and shiftable relatively to said loop-taker into and out of a position effective to wind thread from said thread carrying needle onto said bobbin, said sewing machine frame being formed with an access opening accommodating the said loop-taker and exposing the axial projection of the bobbin journaled in said loop taker for exchanging of said bobbin, the combination of a retractable cover plate for closing said access opening, and mechanism for controlling the winding of thread on said bobbin comprising shifting mechanism operatively engaging said bobbin winding member, means including an operator influenced element operatively connected to said shifting mechanism, and means for supporting said control mechanism on said sewing machine frame with said operator influenced element positioned within said access opening in said machine frame and completely exposed for access by the machine operator through said access opening when said cover plate is retracted.

3. A device as set forth in claim 2 in which said means operatively connected to said shifting mechanism includes a rod endwise slidable in said supporting means substantially parallel to the axis of circular movement of said loop-taker, and in which said operator influenced element comprises a push button carried by said rod beneath said cover plate.

4. A device as set forth in claim 3 in which latch means is provided for constraining said shifting mechanism for said bobbin winder member in the bobbin winding position, a latch control member shiftably supported on said supporting means, and a latch release arm extending from said latch control member adjacent to said push button and completely exposed for access by the machine operator through said access opening when said cover plate is retracted.

5. In a sewing machine having a frame, a thread carrying needle and a circularly moving loop-taker carried in the frame and operatively connected for interrelated movements as are required for the formation of lockstitches, a thread carrying bobbin journaled in said loop-taker and a bobbin winding member interlocked for circular movement with said loop-taker and shiftable relatively to said loop-taker into and out of a position effective to wind thread from said thread carrying needle onto said bobbin, said sewing machine frame being formed with an access opening adjacent to said loop-taker, a cover plate, and means shiftably supporting said cover plate on said sewing machine frame for movement in a constrained path into and out of a retracted position exposing said access opening, mechanism for controlling the winding of thread on said bobbin comprising, shifting mechanism operatively engaging said bobbin winding member, an operator influenced element operatively connected to said shifting mechanism, means for supporting said control mechanism on said sewing machine frame with said operator influenced element accessible to a machine Operator through said access opening when said cover plate is shifted into retracted position, latch means carried by said means for supporting said control mechanism and cooperating with said shifting mechanism to constrain said bobbin winding member in a position operative to influence the winding of thread on said bobbin, a latch release arm associated with said latch means and extending into the constrained path of said cover plate to effect release of said latch means upon movement of said cover plate out of retracted position.

6. In a sewing machine having a frame, a thread carrying needle and a circularly moving loop-taker carried in the frame and operatively connected for interrelated movements are are required for the formation of lockstitches, a thread carrying bobbin journaled in said loop-taker and a bobbin winding member interlocked for circular movement with said loop-taker and shiftable relatively to said loop-taker into and out of a position effective to wind thread from said thread carrying needle onto said bobbin, said sewing machine frame being formed with an access opening adjacent to said loop-taker, a cover plate, and means shiftably supporting said cover plate in said sewing machine frame for movement in a constrained path into and out of a retracted position exposing said access opening, mechanism for controlling the winding of thread on said bobbin comprising a bracket adapted to supporting said entire control mechanism, a spring loaded push rod endwise slidable in said bracket, a lever fulcrumed on said bracket, means carried at one extremity of said lever engaging said push rod, and means carried at the other extremity of said lever engaging said bobbin Winding member, a latch member shiftably supported on said bracket, interengaging latch means on said latch member and on said push rod for constraining said push rod in a position effective to influence winding of thread on said bobbin, a latch release arm associated with said latch member, means for securing said bracket in said sewing machine frame with said push rod accessible to a machine operator through said access opening when said cover plate is shifted into retracted position and said latch re lease arm disposed in said-constrained path of said cover plate for operation engagement of said cover plate with said latch release arm upon' movement of said cover plate out of retracted position.

References Cited UNITED STATES PATENTS 3,103,189 9/1963 Ketterer 112184 3,106,176 10/1963 Doerner 112181 X 3,163,137 1 /1964 Edwards 112-181 3,303,802 2/1967 Crawford 11;2184

HERBERT F. ROSS, Primary Examiner. 

